Idler wheel axle for rail vehicles

ABSTRACT

An idler wheel axle for single-axle or double-axle chassis of rail vehicles having individually mounted wheels and U-shaped, dropped-framed vehicles with lateral carrying legs, wherein each wheel is rotatably mounted on the inside of the associated carrying leg, and on an axle stub of the carrying leg via a wheel mounting, and wherein each wheel is torsionally connected on an inside thereof to a shaft that extends outward through orifices within the wheel and the carrying leg.

BACKGROUND OF THE INVENTION

The present invention relates to an idler wheel axle, and morespecifically to an idle wheel axle assembly for individually mountedwheels.

An idler wheel axle is described in WO 98/24674. This known idler wheelaxle is designed in actual fact as a driven axle, a drive being fastenedto the outside of the chassis frame on each longitudinal side of thechassis. By virtue of a primary suspension provided between the carryingframe and a chassis frame carrying the drive, the drive is connected tothe wheel via a cardanic double coupling. In this case, a firstdrive-side coupling plane is arranged on the outside of the drive and asecond driven-side coupling plane lies directly on the inside of thewheel. The shaft, thereby functioning as a cardan shaft, runscontinuously, with a corresponding length, between the two couplingplanes of the cardanic double coupling. The advantage of this knownidler wheel axle is that the axle and the drive can have a smallconstruction width, in order, for example, to make it possible to haveeven narrow-gage vehicles, at the same time with a small car body width,without the chassis projecting in a disturbing way. A further advantageis that the mounting of the wheel is arranged within the latter, withthe result that a good load-bearing capacity and a long useful life areachieved. This solution has a disadvantage, however, when it isnecessary to have a maximum central-aisle width (as is customary, forexample, in dropped-frame cars) limited only by the spacing of thewheels and necessary transverse-spring travels and transverse-springfree spaces, since this central-aisle width is restricted by thecoupling plane arranged on the inside of the wheel. The fact that accessto wheel components, such as, for example, the wheel mounting, formaintenance work is impeded by the coupling plane may likewise be adisadvantage. Moreover, in the case of adaption to further, for exampleeven smaller gages, virtually the entire construction would have to bechanged.

DE 44 29 889 A1 describes another chassis, in which the wheels, togetherwith the outside drive, are arranged externally on the frame. Here, too,the wheels are connected to the drive in each case via a cardanic doublecoupling, but the driven-side coupling plane lies directly on theoutside of the wheel and the wheel carrying frame is arranged betweenthe insides of the two wheels of an axle. Adaption to different, inparticular smaller gages consequently presents a particular problem.

In the applicant's previous German patent application DE 199 30 424.6,it was proposed, on the basis of WO 98/24674, that the shaft terminatein a coupling plane formed directly on the outside of the carrying leg.This results in particularly high variability in application, especiallywith regard to adaption to smaller gages, while at the same timepreserving the advantage of an optimum design of the wheel mounting bythe latter being arranged within the wheel. Maintenance work is alsomade easier. To adapt the axle to a different, for example smaller gage(for example, 900 mm), it is necessary merely for the length of thewheel-carrying axle stub of the carrying leg and of the shaft to beadapted to the desired wheel position corresponding to the gage. Asregards a driven axle, however, all the drive components can be leftunchanged, because the shaft then forms an intermediate drive shaftwhich is connected to an actual drive shaft in the coupling plane. As aresult, a version, such as is known from the abovementioned DE 44 29 889A1, may be used as a drive unit. All the advantages according to WO98/24674 are nevertheless maintained. Furthermore, in the case of anondriven axle, the shaft may be utilized as a braking shaft by beingconnected to a braking device in the coupling plane.

Moreover, in the proposed idler wheel axle according to DE 199 30 424.6,this provision, in addition to the wheel mounting arranged completelywith two part bearings within the orifice of the wheel, for the shaft tobe mounted in the orifice of the carrying leg via a further rotarybearing which therefore, as a whole, forms a third part bearing.However, in order to avoid tolerance-related errors of alignment betweenthe three part bearings, this version is highly complicated inmanufacturing terms.

SUMMARY OF THE INVENTION

The object on which the present invention is based is to provide such anidler wheel axle, by means of which, while the remaining advantagesdescribed are preserved, optimized stability, particularly in the regionof the wheel mounting, is achieved at a low outlay in manufacturingterms.

This is achieved, according to the invention, in that the wheel mountingconsists of (only) two part bearings, and the first part bearing isarranged within the orifice of the wheel radially between the latter andthe axle stub of the carrying leg, while the second part bearing isarranged, offset axially and radially to the first, within the orificeof the carrying leg radially between the latter and the shaft.

This advantageous configuration affords the appreciable advantage thatthe part bearings, of which only two are provided, can be brought intoalignment in a substantially simpler way. This is a “divided” wheelmounting, the first part bearing being arranged, as before, within thewheel, that is to say in that region of the wheel orifice which isdefined by the axial width or thickness of said wheel. According to theinvention, the second part bearing has been displaced axially into theregion in which the third part bearing was provided in the proposedidler wheel axle. There is therefore virtually a “fusion” of two partbearings. As a result, the wheel, together with the shaft, formsvirtually a unit which is mounted in its entirety via the two partbearings arranged so as to be offset axially, while a bearingload-bearing capacity and therefore useful bearing life which areoptimum in the existing construction space are achieved.

Further advantageous design features of the invention are contained inthe subclaims and the following description.

DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail with reference topreferred exemplary embodiments and examples of use illustrated in thedrawing in which:

FIG. 1 shows a highly diagrammatic top view of a double-axle chassiswith two here, for example, driven idler wheel axles according to theinvention,

FIG. 2 shows the area II from FIG. 1 in an enlarged, more detailedsectional view, two different variants of use being illustrated in theupper and the lower half of the figure,

FIG. 3 shows a design variant of the wheel mounting in a half sectionsimilar to that of FIG. 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 first illustrates by way of example a use of two idler wheelaxles 1 according to the invention in a driven double-axle chassis. Inthis case, on each longitudinal side of the chassis, there is a driveunit 2 which consists of an electric motor 4 and of bevel-wheel gears 6flanged on both sides. Each axle has a U-shaped wheel carrying frame 8which is also known as a gantry axle. Wheels 10 are mounted individuallyon the wheel carrying frame 8, the wheel-carrying frame 8 externallysurrounding the wheels with lateral carrying legs 12, and each wheelbeing articulated rotatably on the inside of the associated carrying leg12. Each drive unit 2 is suspended on a chassis frame, not illustrated,which is supported on the respective wheel carrying frame 8 via aprimary suspension. For this purpose, the wheel carrying frame 8 has, inparticular in the region of the carrying legs 12, bearing surfaces 14for primary spring elements.

As may be gathered from FIG. 2, then, each wheel 10 is torsionallyconnected on its inside to a shaft 16 which extends outward throughorifices 11 and 13 of the wheel 10 and of the carrying leg 12. Thisshaft 16 terminates preferably in a connecting plane 18 formed directlyon the outside of the carrying leg 12. Preferably, the shaft 16 isrigidly connected on its inside to the wheel 10 via a connecting element30, so that the shaft 16 rotates coaxially with the wheel 10.

According to the invention, for the rotary mounting of the wheel 10 orof the unit (wheel/shaft unit) formed from the wheel 10 and the shaft 16as a result of their rigid connection, a wheel mounting 32 is provided,which consists of (only) two part bearings 34 a and 34 b. The first partbearing 34 a is arranged within the wheel 10, that is to say in thatregion of its orifice 11 which is defined by its axial width, that is tosay radially between the wheel 10 and an axle stub 36 of the carryingleg 12, said axle stub engaging into the wheel. The second part bearing34 b is arranged, offset axially and radially to the first part bearing34 a, within the orifice 13 of the carrying leg 12 radially between thelatter and the shaft 16. This configuration according to the inventionshows optimum bearing stress and therefore a high stability of thebearings. Further particulars of the wheel mounting 32 according to theinvention will be explained in more detail further below.

In the example of the use of a driven idler wheel axle 1, as illustratedin the upper half of FIG. 2, the shaft 16 forms an intermediate driveshaft 20 which is connected in the connecting plane 18, via a coupling22, to an actual drive shaft 24 of the drive unit 2. The drive shaft 24is connected on its other opposite side, via a further coupling 26, tothe gear 6 of the drive 2. In the preferred configuration, the driveshaft 24 is designed as a preferably hollow cardan shaft which isessentially coaxial in the prolongation of the intermediate shaft 20 andthe two couplings 22 and 26 located on both sides are designed as acardanic double coupling. In this case, the drive shaft 24 runs throughthe gear 6, so that a drive-side coupling plane 28 lies on the outside,pointing away from the carrying frame 8, of the gear 6 or of the drive2, while the driven-side connecting plane 18 and the coupling 22 liebetween the gear 6 and the carrying leg 12 of the carrying frame 8 (cf.,in this respect, also FIG. 1).

Each coupling 22, 26 consists, in a way known per se, of star-shapedcoupling pieces which engage one into the other, with elastic wedge-likecompensating elements being interposed. As a result, they allow acardanic compensation of suspension movements of an order of magnitudeof at least approximately ±15 mm.

In contrast to the version according to FIG. 2, the shaft 16 connectedto the wheel 10 may also extend continuously, in one piece, as far asthe drive 2 or the coupling 26 (coupling plane 28) located on theoutside there.

The embodiment and form of use of the idler wheel axle 1 according tothe invention, as illustrated in the lower half of FIG. 2, is anon-driven version. In this case, the drive units 2, together withelectric motors 4 and the gears 6, including the drive shafts 24, aredispensed with. Instead, each shaft 16 may then advantageously beutilized as a braking shaft 37 by being connected to a braking device inthe connecting plane 18. In this alternative, the braking device isdesigned preferably as a disk brake, the shaft 16 having connected to ita brake disk 38, so that the latter rotates jointly with the wheel 10.The brake disk 38 cooperates with a brake caliper, not illustrated,supported on the carrying leg 12 of the wheel carrying frame 8. Theconnecting plane 18 of this version which is non-driven, but instead hasbraking capacity, does not have to coincide exactly with the position ofthe connecting plane 18 of the driven version according to FIG. 2.

The wheel mounting 32 according to the invention will be explained ineven more detail below. By virtue of the two part bearings 34 a, 34 bbeing arranged according to the invention, in the first place, the firstpart bearing 34 a has an outer ring 40 seated in the orifice 11 of thewheel 10 and therefore rotating together with the wheel 10 and an innerring 42 seated nonrotatably on the axle stub 36. Furthermore, the secondpart bearing 34 b has an inner ring 44 rotating with the shaft 16 and anouter ring 46 seated non-rotatably in the orifice 13 of the carrying leg12. The two part bearings 34 a, 34 b are in this case designedpreferably as tapered roller bearings for the absorption of radialforces F_(rad) and also of axial forces +F_(a) and −F_(a) acting in thetwo axially opposite directions. Since, according to the invention, thepart bearings 34 a, 34 b are arranged, “reversed”, with respect to theirrotating or non-rotating outer/inner rings, the result of this, whentapered roller bearings are used, is that, for supporting both axialforces, the conical surfaces of the two part bearings 34 a, 34 b do not,in purely geometric terms, run at an opposite inclination to oneanother, as is otherwise customary, but, instead, as seen axially, runat an inclination going in the same direction (mirroring of theeffective direction of force). In a view from the inside of the wheel inthe direction of the outside (from right to left in FIGS. 2 and 3), theconical surfaces of the bearing rings may either narrow according toFIG. 2 or widen according to FIG. 3. The choice between the twoalternatives depends on the forces occurring during the respectiveapplication. As a rule, the version according to FIG. 2 is to bepreferred.

In conclusion, the advantages of the idler wheel axle described will besummarized as follows:

(1) drive components always the same, regardless of the respective gage

(2) a long service life of the wheel mounting due to an optimumarrangement of the two part bearings, regardless of the respective gage

(3) adaption to different gages, with the drive maintained, possiblesolely by the adaption of the intermediate drive shaft and wheelsuspension

(4) high variability of application, thus also for a non-driven axlewith wheels braked via the wheel shaft.

The invention is not restricted to the exemplary embodiments illustratedand described, but also embraces all the versions having the same effectwithin the meaning of the invention. Moreover, the invention hashitherto also not yet been restricted to the feature combination definedin claim 1, but may also be defined by any other combination of specificfeatures of all the individual features disclosed as a whole. This meansthat, in principle, virtually any individual feature of claim 1 may beomitted or be replaced by at least one individual feature disclosedelsewhere in the application. To that extent, claim 1 is to beunderstood merely as a first attempt at the formulation of an invention.

What is claimed is:
 1. An idler wheel axle with individually mountedwheels for chassis of rail vehicles, with a wheel carrying frameexternally surrounding the wheels with lateral carrying legs, each wheelbeing rotatably mounted on the inside of the associated carrying leg,each wheel mounted on an axle stub of the carrying leg by a wheelmounting, and each wheel being torsionally connected on an inside of thewheel to a shaft which extends outward through orifices of the wheel andof the carrying leg, the wheel mounting consisting of two part bearings,and the first part bearing being arranged within the orifice of thewheel between the wheel and the axle stub of the carrying leg, while thesecond part bearing is arranged, offset axially and radially to thefirst, within the orifice of the carrying leg between the carrying legand the shaft.
 2. The idler wheel axle of claim 1, wherein the firstpart bearing has an outer ring rotating with the wheel and an inner ringseated non-rotatably on the axle stub.
 3. The idler wheel axle of claim1, wherein the second part bearing has an inner ring rotating with theshaft and an outer ring seated non-rotatably in the orifice of thecarrying leg.
 4. The idler wheel axle of claim 1, wherein the two partbearings are designed as tapered rollers bearing for the absorption ofradial forces (F_(rad)) and also of axial forces (+F_(a), −F_(a)) actingin the two axially opposite directions.
 5. The idler wheel axle of claim4, wherein the inner and outer rings of the two part bearings includeconical surfaces, and wherein the conical surfaces narrow radially. 6.The idler wheel axle of claim 4, wherein the inner and outer rings ofthe two part bearings include conical surfaces, and wherein the conicalsurfaces widen radially.
 7. The idler wheel axle of claim 1, wherein theshaft terminates in a connecting plane formed directly on the outside ofthe carrying leg.
 8. The idler wheel axle of claim 7, wherein the shaftincludes an intermediate drive shaft that is operably connected in theconnecting plane to a drive shaft of a drive arranged externally on thelongitudinal side of the chassis.
 9. The idler wheel axle of claim 7,wherein the shaft forms a braking shaft and is connected to a brakingdevice in the connecting plane.
 10. The idler wheel axle of claim 9,wherein the braking devices includes a disk brake, and wherein thebraking shaft is operably connected to a brake disk which cooperateswith a brake caliper supported on the carrying leg.
 11. An idler wheelaxle assembly, comprising: a plurality of wheels; a wheel carrying framehaving a plurality of wheel carrying legs, wherein the wheels arerotatably mounted to an inside of the wheel carrying legs such that theframe externally surrounds the wheels; an axle stub operably connectedto each of the wheel carrying legs of the frame by a wheel mounting; anda shaft torsionally connected to an inside of each wheel, the shaftextending outwardly through orifices of each wheel and orifices of eachcarrying leg; wherein the wheel mounting includes a first part bearingand a second part bearing, the first part bearing arranged within theorifice of the wheel between the wheel and the axle stub, the secondpart bearing arranged within the orifice of the carrying leg between thecarrying leg and the shaft, and offset axially and radially to the firstpart bearing, the first part bearing including an outer ring rotatablewith respect to the axle stub and an inner ring seat non-rotatably withthe axle stub, and wherein the second part bearing includes an innerring rotatable with respect to the carrying leg and an outer ring seatednon-rotatably in the orifice of the carrying leg.
 12. The idler wheelaxle assembly of claim 11, wherein the two part bearings are designed astapered rollers bearing for the absorption of radial forces (F_(rad))and also of axial forces (+F_(a), −F_(a)) acting in the two axiallyopposite directions.
 13. The idler wheel axle assembly of claim 12,wherein the inner and outer rings of the two part bearings includeconical surfaces, and wherein the conical surfaces narrow radially. 14.The idler wheel axle assembly of claim 12, wherein the inner and outerrings of the two part bearings include conical surfaces, and wherein theconical surfaces widen radially.
 15. The idler wheel axle assembly ofclaim 11, wherein the shaft terminates in a connecting plane formeddirectly on the outside of the carrying leg.
 16. The idler wheel axleassembly of claim 15, wherein the shaft includes an intermediate driveshaft that is operably connected in the connecting plane to a driveshaft of a drive arranged externally on the longitudinal side of thechassis.
 17. The idler wheel axle assembly of claim 15, wherein theshaft forms a braking shaft and is connected to a braking device in theconnecting plane.
 18. The idle wheel axle assembly of claim 17, whereinthe braking device include a disk brake, and wherein the braking shaftis operably connected to a brake disk which cooperates with a brakecaliper supported on the carrying leg.